This invention relates generally to apparatus for automatically and repeatedly measuring out and discharging predetermined discrete quantities of fluid such as lubricants or coolants and the like from a reservoir containing an ample supply of the same, and for applying the measured amounts of fluid either in finely-divided (e.g., spray or mist) form or normal (as-provided) state to a desired object or article, in particular a cutting tool, workpiece, operating tool, bearing chain or the like. In a more particular sense, the invention relates to an apparatus of the type just described which pneumatically functions to produce a generally uniform application mist of lubricant, coolant, or other liquid, having regular and continuous but selectively variable density, responsive to a flow of compressed gas, wherein said liquid and said compressed gas are transported together through a single outlet tube, or separately through a coaxial outlet tube, to the point of application.
In a still more particular sense, the apparatus of the invention provides a device of this character in which the discharge of the fluid, whether in aerated form, or normal state, occurs in response to a given command signal or condition and is terminated in response to such a signal or condition. In particular, such a signal may be the presence of compressed air used for operating pneumatic tools, or generated in response to activation of a machine utilized to accomplish an industrial manufacturing operation such as cutting or drilling, in which environment the lubricant or coolant metered from the apparatus is applied to the cutting tool or workpiece in mist form, either on a generally continuous basis or in recurrent bursts of selected frequency.
In industrial operations, particularly in cutting and machining operations, it has long been recognized that it is highly desirable to apply liquid lubricants or coolants to the cutting tools or workpieces, and often to the power tools as well, throughout duty cycles. Sometimes such coolants and lubricants are applied as a generally continuous stream, and sometimes in mist or "atomized" form, for example, sprayed from an appropriate nozzle. In other operations, a succession of droplets is sometimes selected as the preferred form of application. In all of these situations, the quantity of the lubricant/coolant which must be applied is usually the principal determinator of the form of application to be selected, although many other factors may also enter into that selection.
Where the required amount of lubricant or coolant is comparatively small, the regulation of applied quantities becomes a difficult matter. This is particularly true where the desired form of application is mist or spray. Sometimes it is desirable to have a sequence of mist or spray pulses applied to the drill bit, tap and/or the workpiece being drilled during each cycle of drilling operation, but not during intervals when the tool is not actually in use. However, during such use of the tool, the operator has his attention and energy devoted to the drilling task, and cannot be expected to execute or issue periodic stop/start coolant/lubricant supply commands.
Accordingly, it has been proposed heretofore to provide a modular self-regulating supply apparatus for lubricant and coolant in industrial circumstances such as those referred to above, in particular an apparatus of this type which is adapted to cooperative operation in a machining, stamping or air tool environment, and capable of operating on a repeating, cyclical, pulsatory basis to dispense a succession of metered pulses of the lubricant or coolant fluid during each cycle of machine operation. Such devices may be self-contained and adapted to be mounted directly on or near the machine or air tool, and to operate in direct response to on/off signals used to control operation of the the air tool or other machine.
The aforementioned known modular apparatus comprises cyclically operative, pulsatory, lubricant or coolant dispensing means which provide for selective variation in the amount of fluid dispensed in each cycle of operation, as well as the form (spray or normal). Further, these devices feature control means for the lubricant dispensing function whereby their pulsatory operational activity is made selectively variable in frequency. Thus, by use of such apparatus, once the air tool or other such primary device is triggered into operation, both the frequency and amount of applied lubricant or coolant may be selectively regulated to suit the particular task. Additionally, such known devices make it possible to provide periodically metered amounts of lubricant or other liquid in the form of either droplets or mist, as may be required.
Although the known apparatus described above is a highly useful and innovative development which provides many advantages in actual use, it requires use of coaxial tubes or other such dual conduits to separately convey the liquid lubricants or coolants to the cutting tools or workpieces, along with the compressed air or other gas used to "atomize" the liquid into mist form at or near the point of application and apply it to the tool or workpiece. That is, the compressed air is conveyed through one tube of a coaxial pair, and lubricant/coolant is provided through the other such tube. At the remote end of the coaxial tube, the compressed air and lubricant/coolant are mixed as they are dispersed, typically by using a desired nozzle. Because the compressed air and lubricant/coolant must be supplied separately through coaxial or other duplicate tubes, this approach requires that a relatively complex, and more costly, manifold be provided, along with the coaxial tubing, which is also more expensive. Additionally, the coaxial nozzle which mixes and disperses the liquid from the interior tube by using the compressed gas carried in the exterior tube adds expense and further complexity.